Breckinridge attended the University of Tennessee in 1897 and 1898. He was appointed as a second lieutenant in the Marine Corps in 1899 to fight in the Spanish–American War, seeing service at Cavite in the Philippines. He was promoted to captain on July 23, 1901, serving as the commander of Marine detachments at sea through that decade. He served ashore in Panama and Nicaragua from late 1909 to early 1911, months later, temporary expeditionary duty in Cuba. In April 1914, he participated in the United States occupation of Veracruz while in command of the Marine attachment from the USS Utah. He received a commendation for his conduct in battle.
Breckinridge served during World War I as naval attaché at many diplomatic posts from April 1916 to September 1918, to include Petrograd, Russia, Christiania, Norway, Copenhagen, Denmark, and Stockholm, Sweden. His service would earn him the Navy Cross, for "distinguished service in the line of his profession as Naval Attache to the American Legations at Christiana and Stockholm, and for a time also at Copenhagen. At all of these posts of duty, the service of information established and conducted was of great value to the United States and allied Powers." He was promoted to major on June 12, 1916, to lieutenant colonel two months later, and to colonel on July 1, 1918.
From January 28, 1930 until March 13, 1932, Breckinridge commanded the Marine Detachment at the American Legation, Peiping, China, and was promoted to brigadier general on October 31, 1931. Following this, he returned to Quantico to command Marine Corps Schools again until January 6, 1935, having been promoted to major general on February 1, 1935. He was ordered to San Francisco, California, to assume command of the Department of the Pacific until June 24, 1937, when he again returned to Quantico as commander until September 1939. He then commanded Marine Barracks, Parris Island, South Carolina until his retirement effective October 1, 1941, having attained the statutory retiring age of 64 years. He received a promotion to lieutenant general at that date in recognition of his decorated service as a combat veteran.
